Biology · Evolution · NEET
It is the evidence for evolution that comes from the study of fossils. NCERT says the study of fossils in different sedimentary layers shows that life-forms varied over time, and that new forms of life arose at different times in Earth's history. All of this together is called paleontological evidence.
Fossils are the remains of the HARD parts of life-forms found in rocks (like bones, shells, teeth). Soft parts usually decay and are not preserved. NEET often tests this exact wording, so remember 'hard parts found in rocks'.
Rocks form sediments one over the other during Earth's long history. The bottom layer formed first (oldest), and each new layer settles on top. So organisms that died earlier are trapped in deeper layers, and later organisms are in upper layers. Different-aged rock sediments therefore contain fossils of different life-forms.
By radioactive dating (also called radioactive-dating). It uses the fixed rate of decay of radioactive elements to find how old the fossil or its rock layer is. NCERT directly reminds you of the 'method of radioactive-dating' when discussing fossil ages.
A sediment is a layer of settled rock material that builds up over time. A fossil is the preserved hard remains of an organism trapped inside that sediment. The sediment is the 'page' and the fossil is the 'writing' on it.
It shows that life-forms are often restricted to certain geological time-spans, that life changed over time, and that new forms appeared at different times. Some fossils resemble modern organisms; others (like dinosaurs) are extinct. This supports that evolution has taken place.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
It is treated as strong evidence because fossils are actual physical remains of past organisms. It directly shows that life-forms existed in the past, changed over time, and that new forms arose at different periods.
It shows some fossils that appear similar to modern organisms, along with extinct forms such as dinosaurs, to illustrate how fossils record past life-forms in rock sediments.
No. NCERT notes that some fossils appear similar to modern organisms, while others (like dinosaurs) represent extinct organisms. Both types are useful evidence.
Radioactive dating. It measures the decay of radioactive elements to estimate the age of the fossil-bearing sediment, letting scientists place fossils in the correct geological period.
Yes. It is a high-yield one-mark topic in the Evolution chapter. Direct NCERT-line questions on 'hard parts in rocks', 'different-aged sediments', and 'radioactive dating' are commonly asked.
